6/09/2017

On 6/6/2017 Microsoft finally announced availability of SharePoint Framework Extensions Developer Preview - a set of allowed customizations to change user experience of sites, lists and document libraries. Drawing a parallel between "classic" SharePoint development and new features - this is a new iteration of JSLink, ScriptLink and custom actions.
Let's review currently available extensions and their usage.UPDATE: on 8/29/2017 Release Candidate was announced. The post is updated to contain newer version of API.